The router protocol versions section in dir-spec is out of date

I doubt clients do this: they only download the consensus, not votes:

A client should believe that a router supports a given feature if that
   feature is supported by the router or protocol versions in more than half
   of the live networkstatuses' "v" entries for that router.

https://gitweb.torproject.org/torspec.git/tree/dir-spec.txt#n3493